Rotary cutter of mower

ABSTRACT

A rotary cutter for a mower is provided wherein the cord delivering operation, which is necessary when the free end of the cord is worn, is carried out only when the rotary cutter is rotated at a low speed or is stopped. The rotary cutter includes a cord for cutting grass upon rotation thereof, a reel which holds the cord and allows delivering of the cord while the reel is intermittently rotated, a cover for a case which houses the reel, and a press body which protrudes downwardly from the case and is movable in an axial direction upon pressing so as to intermittently rotate the reel. A return spring for biasing the press body in a direction to protrude the press body from the case between the reel and the press body is also provided. The press body and the case engage each other such that the press body is slidable in an axial direction while preventing relative rotation with each other. By pressing the press body against the biasing return spring, a set of protrusions formed on the press body are detachably engaged with protrusions formed on the reel so as to intermittently rotate the reel.

FIELD OF THE INVENTION

The present invention relates to a rotary cutter of a mower forperforming a mowing operation of grass or the like with a cord radiallyextended from a case which is rotatably driven by an engine or the likeby way of a shaft.

DESCRIPTION OF THE PRIOR ART

Conventionally, a system which accommodates a cord in a reel has beenused as this kind of technique. To deliver the cord when the free endside of the cord is worn, an engine is stopped and a cutter portion ispartially disassembled, or bolts are loosened, or, as disclosed inJapanese Laid-open Publication SHO57-5608, a press body for moving areel in an axial direction is mounted on a distal end of mounting shaftof a cutter and this press body is pushed into the reel while the cutteris rotated so that the phase between the reel and a housing is slippedthus enabling the delivering of the cord.

In the conventional rotary cutters having the above-mentionedconstitutions, however, the former necessitates an extremely cumbersomemanipulation for delivering the cord, while the latter pushes the pressbody into the reel by strongly striking the press body while the rotarycutter is rotated, the free end side of the cord is lowered and hence,the cord scatters pebbles or the like thus making the mowing operationdangerous. Further, in disassembling the rotary cutter, respective partsare separated and there has been a problem that extremely cumbersomesteps and an utmost care become necessary in reassembling.

Further, in case the shape of the mower side is different, there hasbeen a case that the cover cannot be mounted and hence, depending on themower, the rotary cutter cannot be used.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a rotary cutter of amower which can overcome the above-mentioned technical problems and isconstructed such that the cord delivering operation which becomesnecessary at the time that the free end side of the cord is worn out,can be carried out only at the time of the low speed rotation or thenon-rotation of the rotary cutter so that the scattering of pebbles canbe prevented and respective parts are prevented from being separated atrandom at the time of disassembling thus facilitating the reassembling,and a cover can be replaced depending on the shape of the mower side.

To achieve the above-mentioned object, the rotary cutter of the presentinvention includes a cord for carrying out a mowing of grass or the likealong with a rotation thereof, a reel which accommodates the cord andallows delivering of the cord, while being intermittently rotated, acover which covers a case accommodating the reel, and a press body whichis protruded downwardly from the ease and is movable in an axialdirection by pressing so as to intermittently rotate the reel, whereinthe improvement is characterized in that means for biasing the pressbody in a direction to protrude the press body from the case is disposedbetween the reel and the press body, the press body and the case areengaged with each other such that the press body is slidable in an axialdirection while a relative rotation between them is prevented, and bypressing the press body against the biasing means, a set of protrusionsformed on the press body are engaged with or disengaged from protrusionsformed on the reel so as to intermittently rotate the reel. Further, itis preferable to form an elongated hole in the reel into which one of aset of protrusions formed on the press body is fitted. Further, it ispreferable to construct the rotary cutter of the mower such thatratchets held in place by the biasing means are expanded by acentrifugal force generated by the high speed rotation of the rotarycutter so as to prevent the axial slide movement of the press body.Further, it is preferable that the biasing means is constituted by areturn spring disposed between the reel and the press body. Further, itis preferable that resiliently deformable pawls which are formed on thecentral portion of the press body are engaged with a cylindrical portionformed on the central portion of the reel. Furthermore, it is preferablethat the cover is constituted by either a plastic member provided with afemale threaded member at a central portion thereof for mounting therotary cutter to the mower or a thin metal plate member provided with ahole at a central portion thereof for mounting the rotary cutter to themower.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a rotary cutter of a mower of oneembodiment of the present invention in a non-rotating condition or in alow-speed rotating condition.

FIG. 2 is a cross sectional view of a rotary cutter of a mower of oneembodiment of the present invention in a high-speed rotating condition.

FIG. 3 is a cross sectional view of a rotary cutter of a mower of oneembodiment of the present invention in a low-speed rotating conditionwith a press body in a pressed condition.

FIG. 4 is an exploded cross sectional view of a rotary cutter of a mowerof one embodiment of the present invention.

FIGS. 5a-5 d are an explanatory view of a rotary cutter of a mower ofone embodiment of the present invention showing the condition where acord is delivered from a reel.

FIG. 6 is a cross sectional view of a rotary cutter of a mower ofanother embodiment of the present invention in a non-rotating conditionor in a slow-speed rotating condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A rotary cutter of a mower of one embodiment of the present invention ishereinafter explained in detail in conjunction with attached drawings.

In the present invention, as shown in FIG. 1 to FIG. 5, a reel 1 isrotatably accommodated in a case 2 made of a bottomed cylinder. The reel1 accommodates a cord or cords 7 which have the peripheral portionsthereof formed of nylon. The reel 1 is provided with means (not shown)which fixedly secures a central portion of the cord 7 (in a case whereone cord is used) or one end portions (in a case where two cords areused). A recess groove 1-2 divided in two by an annular wall 1-1 whichprevents an entanglement of the cord is formed on the outer peripheralportion of the reel 1. Further, a through-hole 1-3 is formed in thecentral portion of the reel 1 and a plurality of protrusions 1-4 whichprotrude inwardly are formed in an equally spaced-apart manner in acircumferential direction on an inner surface of the through-hole 1-3.Further, a cylindrical portion 1-6 which is supported by a flange 1-5extending in a radial direction is integrally provided in the inside ofthe through-hole 1-3. The cylindrical portion 1-6 and through hole 1-3are disposed coaxially, while a plurality of elongated holes 1-8 areformed in the flange 1-5 on the same circumference in an equallyspaced-apart manner.

The case 2 is provided with an outlet 2-1 for letting the cord 7 out ina direction opposed to the outer peripheral surface of the case 2 and acircular hole 2-3 is formed in the central portion of a bottom portion2-2 of the case.

Hooks 2-5 which are directed outwardly are formed on the open-ended edgeportion of the case 2 and these hooks 2-5 are constructed such that theycan be engaged with holes 3-1 formed in the outer peripheral portion ofa cover 3 which is mounted such that it covers the entire surface of theopen-ended edge portion of the case 2. That is, by fitting the hooks 2-5into the holes 3-1, the cover 3 can be replaceably mounted on the case2. A housing A is constituted by the case 2 and the cover 3.

Further, a female thread member 3-2 for mounting the rotary cutter tothe mower is fixedly secured to the central portion of the cover 3 and athreaded portion 3-3 in which a shaft portion (not shown) of a mowerbody is screwed is provided to the female thread member 3-2.

On the other hand, in the inside of the housing A which is formed by thecase 2 and the cover 3, a press body 4 made of a bottomed cylindricalbody is accommodated. The press body 4 is fitted into the inside of thethrough-hole 1-3 and is biased by a return spring 6 such that the bottomportion thereof is protruded through the circular hole 2-3 of the case2. On the open peripheral portion of the press body 4, a plurality ofprotrusions 4-1 which are protruded upwardly and outwardly are formed inthe same equally spaced-apart manner corresponding to the protrusions1-4 formed on the inner peripheral surface of the reel 1. Further, aplurality of arm-like resilient ribs 4-3 are axially protruded from abottom portion 4-2 of the press body 4 and pawl portions 4-4 which areformed on free ends of the ribs 4-3 are engaged with the annularshoulder portion 1-7 of the cylindrical portion 1-6 disposed in theinside of the through-hole 1-3 of the reel 1.

Protrusions 4-5 are formed on the outer peripheral surface of the pressbody 4 such that the protrusions 4-5 extend in an axial direction, whilerecessed grooves 2-7 which extend in an axial direction are formed onthe inner peripheral surface of a cylindrical wall 2-6 which protrudesin an axial direction from the peripheral portion of the circular hole2-3 of the case 2. By engaging the protrusions 4-5 with the recessedgrooves 2-7, a constitution which prevents the relative rotation betweenthe case 2 and the press body 4 but allows the relative slide movementin an axial direction is formed.

The return spring 6 is extended such that the return spring 6 has oneend thereof brought into contact with the bottom portion 4-2 of thepress body 4 so as to bias the press body 4 in a downward direction andthe other end brought into contact with the short side portions 5-2 ofapproximately L-shaped ratchets 5 which are pivotably mounted on theflanges 1-5 by way of pivoting shafts 5-1. Due to such a constitution,unless a centrifugal force generated by a high-speed rotation is appliedto the housing A made of the case 2 and the cover 3, that is, at thetime of non-operating (stop) condition or at the time of low-speedrotation, the long side portions 5-3 of the L-shaped ratchets 5 arepositioned parallel to the inner peripheral wall of the press body 4(see FIG. 1), while once the housing A is rotated at a high speed, thecentrifugal force acts on the long side portions 5-3 against the returnspring 6 and expands the free ends 5-4 of the long side portions 5-3 inan outwardly radial direction so that the long side portions 5-3 areengaged with the annular shoulder portion 4-6 formed on the innerperipheral surface of the press body 4 (see FIG. 2).

Subsequently, to explain the positional relationship between theprotrusions 4-1 and the protrusions 4-5 formed on the press body 4 andthe protrusions 1-4 formed on the through-hole 1-3 of the reel 1, theprotrusions 4-1 and 4-5 have their phases shifted axially from eachother and they have their phases shifted also in a circumferentialdirection at an interval larger than the width of the protrusions 1-4 ofthe reel 1. That is, the width of the protrusions 1-4 of the reel 1 isdesigned such that when the press body 4 is slid in an axial direction,the protrusions 1-4 of the reel 1 are moved and positioned in the spacesdefined between the protrusions 4-1 and the protrusions 4-5 of the pressbody 4.

The manner of operating the rotary cutter of the mower of the presentinvention having the above-mentioned constitution is explainedhereinafter.

Firstly, in the non-operating condition or in the low-speed rotatingcondition, as shown in FIG. 11, the press body 4 is biased downwardly bymeans of the return spring 6, while the annular shoulder portion 1-7 inthe inside of the cylindrical portion 1-6 of the reel 1 and the pawls4-4 formed on the distal ends of the resilient ribs 4-3 of the pressbody 4 are engaged with each other and hence, a further downwardmovement of the press body 4 is prevented. In this condition, thebiasing force of the return spring 6 acts on the short side portions 5-2of the ratchets 5 and hence, the long side portions 5-3 of the ratchetsare held in parallel with the inner peripheral wall of the press body 4.

Subsequently, when the mower starts the high-speed rotation, thisrotation brings about the rotation of the whole cover 3 by way of theshaft female-threaded member 3-2 and the case 2 is integrally rotatedwith the cover 3 due to the engagement between the hole 3-1 and the hook2-5 and hence, whole the housing A is rotated. Due to the engagementbetween the recessed grooves 2-7 formed on the cylindrical wall 2-6 ofthe case 2 and the protrusion 4-5 formed on the outer peripheral surfaceof the press body 4, the press body 4 is also rotated integrally withthe housing A. Further, since the protrusions 4-1 of the press body 4are engaged with the protrusions 1-4 of the reel 1, the housing A andthe reel 1 are integrally rotated. Due to this rotation of the reel 1,the cord 7 which is fixedly secured to the recessed groove 1-2 of thereel 1 and is extended outwardly through the opening 2-1 is rotated andmows lawn, grass or the like with the free end portion thereof.

In this manner, at the time of the high-speed rotation of the housing Aconstituted-by the case 2 and the cover 3, the centrifugal force acts onthe long side portions 5-3 of the ratchets 5 and the free ends 5-4 ofthe long side portions 5-3 are expanded in an outward radial directionagainst the return spring 6 and take a position shown in FIG. 2 wherethe free ends 5-4 can be engaged with the shoulder portion 4-6 of thepress body 4 and hence, even when the press body 4 is strongly struck inthe ground, the press body 4 is prevented from moving upwardly by anaxial slide movement thereof.

On the other hand, in case the free end side of the cord 7 being used isworn out and the cord 7 becomes short, it becomes necessary to deliverthe cord 7 from the reel 1. In such a case, at the time that nocentrifugal force acts on the long side portions 5-3 of the ratchets 5so that the long side portions 5-3 are held in parallel with the innerperipheral surface of the press body 4 whereby the housing A is rotatedat a low speed (see FIG. 5(a)), the press body 4 is struck in the groundas shown in FIG. 3 so as to move the press body 4 upwardly against thereturn spring 6.

Here, along with the upward movement of the press body 4, theprotrusions 4-1 are moved together (see FIG. 5(b)) so that theprotrusions 4-1 are disengaged from the protrusions 1-4 of the reel 1.Accordingly, although the press body 4 to which the rotation of themower is directly transferred maintains its rotation at the presentrotational speed, the rotation of the reel 1 which is disengaged fromthe protrusions 4-1 of the press body 4 is carried out only by theinertia and hence is lowered. Due to such lowering of the rotationalspeed of the reel 1, the rotation of the press body 4 precedes therotation of the reel 1 and the protrusions 4-5 take a condition wherethe protrusion 4-5 are brought into contact with succeeding protrusions4-1 of the downstream side in a rotating direction (see FIG. 5(c)).Then, due to the restoring force of the return spring 6, the press body4 is moved downwardly and the succeeding protrusions 4-1 of the pressbody 4 return to the position of the protrusions 1-4 of the reel 1 (seeFIG. 5(d)). Subsequently, the succeeding protrusions 4-1 of the pressbody 4 are brought into contact with the succeeding protrusions 1-4 andtake the position shown in FIG. 5(a). That is, the reel 1 isintermittently rotated by the distance between the protrusions 1-4 ofthe reel 1.

In this manner, at the time of the low speed rotation of the housing A,every time the press body 4 is struck in the ground, the cord 7 isdelivered from the reel 1 by the length corresponding to thecircumferential distance between the protrusions 1-4 and hence, if anoperator strikes the press body 4 in the ground given times, the cord 7of the given length is delivered from the reel 1.

On the other hand, in case the cord 7 is delivered at the time therotary cutter is stopped, firstly, the press body 4 is struck in theground and the press body 4 is moved upwardly against the return spring6. Here, since the rotary cutter is not rotated, inclined surfaces 4-1 aformed on the rear brim portions of the upper end of the liftedprotrusions 4-1 at a downstream side in a rotating direction are broughtinto contact with inclined surfaces 1-8 a formed in an equallyspaced-apart manner on the front brim portions of the lower end of aplurality of elongated holes 1-8 formed in the flange 1-5 of the reel 1at an upstream side in a rotating direction. Due to such a contact ofthese inclined surfaces, the elongated holes 1-8 are slightly pushed ina rearward direction as shown in FIG. 5(b). Subsequently, the press body4 is lowered due to the restoring force of the return spring 6 andhence, the protrusions 4-1 of the press body 4 take a condition wherethey run aground the protrusions 1-4 of the reel 1. Here, if theoperator pulls the cord 7, the reel 1 is rotated in a reverse directionand the protrusions 4-1 are slid on the upper surfaces of theprotrusions 1-4 to take the position shown in FIG. 5(d), whereby thecord 7 can be delivered.

Accordingly, in this case, when the operator strikes the press body 4 inthe ground given times so as to deliver the cord 7, the cord 7 is alsodelivered a given length from the reel 1.

Then, in case the cord 7 of the rotary cutter of the mower according tothe present invention is worn so that the cord must be replaced or incase the rotary cutter must be disassembled to exchange or inspect theparts inside the rotary cutter for repairing, firstly the hooks 2-5 ofthe case 2 is disengaged from the holes 3-1 of the cover 3 so that thecase 2 can be removed downwardly. Then, the reel 1 and the press body 4are removed from the cover 3 and the cord 7 is replaced. In such anoperation, the press body 4 which incorporates the return spring 6 andthe approximately L-shaped ratchets 5 therein is not separated from thereel 1 due to the engagement between the pawl portions 4-4 formed on thedistal end portions of the arm-shaped resilient ribs 4-3 of the pressbody 4 and the annular shoulder portion 1-7 of the cylindrical portion1-6 disposed inside the through-hole 1-3 of the reel 1 and hence, thereassembling becomes extremely easy.

In replacing the return spring 6 and the approximately L-shaped ratchets5 incorporated in the inside of the press body 4, to disengage the pawlportions 4-4 from the annular shoulder portion 1-7, the press body 4 isstrongly pulled downwardly. Due to such a pulling operation, thearm-shaped resilient ribs 4-3 are deflected and hence, the press body 4can be removed from the reel 1 thus the press body 4 and the reel 1 canbe separated from each other.

Further, in case the press body 4 is to be reassembled to the reel 1,the ratchets 5 and the return spring 6 are firstly incorporated in theinside of the press body 4 and thereafter the resilient ribs 4-3 of thepress body 4 are forcibly pushed into the inside of the cylindricalportion 1-6 of the reel 1 in an axial direction. Due to such anoperation, contrary to the above-mentioned disassembling operation, thediameter of the deflectable pawl portions 4-4 of the arm-shapedresilient ribs 4-3 is narrowed by the annular shoulder portion 1-7 andthen after getting over the annular shoulder portion 1-7, the arm-shapedresilient ribs 4-3 are expanded to take the original condition due tothe resiliency of the resilient ribs 4-3 so that the condition where thepawl portions 4-4 are engaged with the annular shoulder portion 1-7 isobtained.

In the embodiment which has been explained heretofore, although thecover 3 is explained as one which is molded by plastic material and isprovided with a female threaded member for mounting the rotary cutter tothe mower at the central portion thereof, the rotary cutter of the mowerof the present invention may be Constituted such that a cover 3′ isformed of a thin metal plate as shown in FIG. 6 and a hole 3′-1 formounting the rotary cutter to the mower is formed in a central portionthereof.

In this manner, the shape of the mounting portion of the covers 3, 3′ tothe mower can be suitably selected and hence, the rotary cutter can beused while replacing the cover depending on the shape of mower side.

As has been described heretofore, according to the present invention,the cord delivering operation which becomes necessary when the free endside of the cord is worn can be carried out only when the rotary cutteris rotated at a low speed or is not operated (stopped). Accordingly, thepresent invention can provide the rotary cutter of the mower which hasadvantages that the scattering of the pebble stones can be prevented,parts are not separated at random at the time of disassembling therotary cutter so that reassembling is facilitated, and the cover can bereplaced depending on the shape of the mower side.

What is claimed is:
 1. A rotary cutter of a mower comprising a cord formowing grass upon rotation thereof, a reel which removably holds saidcord and serves to deliver said cord while said reel is intermittentlyrotated, a cover for a case which contains said reel, a unitary pressbody which protrudes downwardly from said case and is movable in anaxial direction upon pressing so as to intermittently rotate said reel,and a means for biasing said press body in a direction to protrude saidpress body from said case, wherein said means for biasing is disposedbetween said reel and said press body, said press body and said case areengaged with each other such that said press body is slidable in anaxial direction while relative rotation between said press body and saidcase is prevented, and upon pressing said press body against said meansfor biasing, a set of protrusions formed on said press body aredetachably engaged with protrusions formed on said reel so as tointermittently rotate said reel.
 2. A rotary cutter of a mower accordingto claim 1, wherein said reel includes an elongated hole into which oneof the set of protrusions formed on the press body fits.
 3. A rotarycutter of a mower according to claim 1, further comprising ratchetswhich are held in place by said means for biasing and which areconstructed and arranged to expand upon centrifugal force generated byhigh speed rotation of said rotary cutter to prevent axial slidemovement of said press body.
 4. A rotary cutter of a mower according toclaim 3, wherein said means for biasing is a return spring disposedbetween said reel and said press body.
 5. A rotary cutter of a moweraccording to claim 1 further comprising deflectable pawls which are partof a central portion of said press body and are engaged with acylindrical portion formed on the central portion of said reel.